How is phenolphthalein used to distinguish between sodium carbonate and sodium bicarbonate.

Explanation

Sodium carbonate is more soluble and furnishes two moles of hydroxyl ions per mole.
Sodium bicarbonate is less soluble and furnishes one mole of hydroxyl ions per mole.
Aqueous sodium carbonate solution is basic and phenolphthalein is pink .
Aqueous bicarbonate is also basic, but `[OH^(-)]` is not sufficient to give pink colour with phenolphthalein.